An electronic device usually has a connecter, such as a mini jack, for connecting the electronic device with another electronic device, so as to transmit and receive signals. In order to connect between electronic devices by using such connecter, plugs provided at both ends of a connecting cable are respectively inserted into connecters of the electronic devices.
The connecter and the plug are disclosed, for example, in Japanese Publication for Utility Model, No. 3041482 (registration date: Jul. 2, 1997). FIG. 7 shows an arrangement of such connecter and the plug. As shown in FIG. 7, a plug 801 has a large diameter portion 802 at an end thereof, and a small diameter portion 803, which is a narrow portion, next to the large diameter portion 802. A connecter 811 has an inter-fitting section 812, which is, for example, made of a blade spring, for holding the plug.
In order to plug-in the plug 801 in the connecter 811, the plug 801 is inserted into the connecter 811 in the A-direction. When the plug 801 is inserted into the connecter 811, the inter-fitting section 812 is pressed by the plug 801, so as to be pushed away, along a surface of the large diameter portion 802, in a direction perpendicular to the direction in which the plug is inserted. Afterwards, when the large diameter portion 802 passes beyond the inter-fitting section 812, the inter-fitting section 812 is fitted with the small diameter portion 803 of the plug 801. This state is hereinafter referred to as a plug-in state of the plug 801 in the connecter 811.
In order to detach, from the connecter 811, the plug 801 in the plug-in state, the operation described above is reversed, so that the large diameter portion 802 directly displaces the inter-fitting section 812 of the connecter 811 as the plug 801 moves in a detaching direction (a direction opposite to the A-direction). Because the large diameter portion 802 directly displaces the inter-fitting section 812, it is possible to detach the plug 801 from the connecter 811 by applying a relatively weak force to the plug 801. Moreover, if a force applied to the plug 801 is strong enough to detach the plug 801 from the connecter 811, the plug-in state of the plug 801 in the connecter 811 is maintained.
Japanese Publication for Utility Model, No. 3041482 also discloses another connecter 821, which is, as shown in FIG. 8, an improvement of the connecter 811 shown in FIG. 7, having an inter-fitting section 822. A basic structure of the connecter 821 and operation for inserting and detaching a plug into and from the connecter 821 are the same as those of the connecter 811.
The plug 801 and the connecter 811 are advantageous in that the plug 801 and the connecter 811 are inexpensive, have simple structures, and that it is easy to insert and detach the plug 801 into and from the connecter 811. On the other hand, because the plug 801 is easily detached from the connecter 811 with a weak force, it is likely that accidental interruption occurs in transmitting and receiving signals between electronic devices that are connected with each other by a cable. In particular, in connecting between stationary electronic devices, there has been a problem that the plug 801 is detached due to vibration if the plug 801 and the connecter 811 are insufficiently matched.
According to the art disclosed in the publication, the cable is an electronic cable. However, it can easily be expected that it is possible to hold an optical fiber cable in a similar manner, and that interruption may occur in transmitting and receiving signals because the cable is easily detached.
Meanwhile, for example, in an optical plug connecter for Ethernet (a registered trademark) and an optical plug connecter disclosed in Japanese Publication for Unexamined Patent Application, Tokukai, No. 2000-147317 (publication date: May 26, 2000), in order to prevent the plug from being detached accidentally as described above, a mechanical lock is adopted for connecting between the plug and the connecter.
For example, according to the art disclosed in Japanese Publication for Unexamined Patent Application, Tokukai, No. 2000-147317, as shown in FIG. 9, a plug 831 is provided at an end of an optical fiber cable 833, and a claw portion 832 sticks out from a body portion of the plug 831. The claw portion 832 is fitted together with an engaging portion 842 of the connecter 841 when the plug 831 is inserted into the connecter 841. Because of this, it is possible to prevent the plug 831 from being accidentally detached from the connecter 841. In order to detach the plug 831 from the connecter 841, the plug 831 is pulled in the detaching direction while pressing the claw portion 832 toward the body of the plug 831.
However, because the mechanical lock plug 831 shown in FIG. 9 has, in addition to the body of the plug 841 to be inserted into the mechanical lock type connecter 841, the claw portion 832 sticking out pf the body of the plug 841, it is difficult to downsize the mechanical lock plug 831 due to the structure thereof. Furthermore, it is necessary that the connecter 841 has the engaging portion 842 for engaging the claw portion 832, and that an electronic device including the connecter 841 has space for installing the engaging portion 842 therein. Therefore, there is a problem that connecting portions of the plug 831 and the connecter 841 become large.
Moreover, because the mechanical locks used in the plug shown in FIG. 9 and in Ethernet (registered trademark) are so arranged that it is necessary to confirm a rotative direction of the plug in using a lock mechanism provided to the plug, insertion of the plug into the connecter is complex.